SC4910B datasheet(12/19 Pages) SEMTECH

12 / 19 page

 2005 Semtech Corp.

www.semtech.com

SC4910A/B

POWER MANAGEMENT

Load Remote Sensing

Dedicated -SENSE pin provides true remote sensing of

the regulated supply’s output terminal voltage for high

current applications. As shown in Figure 5, the bandgap

reference “ground “ is brought out as –Sense, which is

connected to the “load ground” and to the local analog

ground by the resistor R10. With this way combined with

upper side R1, the voltage drop on power line is offset

and the load voltage is truly sensed.

LOAD

R10

SC4910

COMP

OUTB

ISHARE

PHASE

OUTA

RT1

RT2

-SENSE

DELAY

SY NC/EN

VREF

Figure 5

Load Current Sharing

A single wire connected between the ISHARE pins will

force current sharing between parallel units for paralleling

or n+1 redundant operation.

The ISHARE pin allows for current sharing between several

parallel units. The ISHARE pin connects internally to the

non-inverting input of ISHARE amplifier. An internal 4K

Ω

resistor is between the inverting and non-inverting inputs

of this amplifier, with the inverting input also connected

to the COMP pin. The output of the amplifier connects

to the SS (0.75V ref) pin. During normal operation, when

all devices are sharing the load current equally, the COMP

pin voltages on each units should be approximately equal.

If one of the devices begins to take on too much or too

little of the load, the difference in COMP pin voltage will

cause the ISHARE amplifier to adjust the SS (0.75V ref)

voltage accordingly. In the event of ISHARE pulled down

below 1V, the ISHARE amplifier is disabled to prevent

output voltage of the unit lower than specification.

Applications Information (Cont.)

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